The Flight Dynamics Analysis Branch (FDAB) has the capability to perform the design, analysis, simulation, testing, integration, and operation of the both the onboard attitude control system (ACS) and the ground attitude determination system for a spacecraft. We can perform combinations of these functions as needed to support both in-house built spacecraft as well as out-of-house built spacecraft. Oversight and support for out of house spacecraft involve less design and analysis, but more technical review and contractor management.

During the design phase of spacecraft development, the FDAB can select the sensor and actuator complement appropriate to meet mission requirements. The FDAB engineers provide valuable analysis and simulation capability to instrument teams and to missions in the early development or research stage. This support may include sensor complement studies, control system performance evaluation, or simulation of new and novel control system architectures. In addition, FDAB plans the maneuvers necessary to calibrate the attitude sensors and any other attitude maneuvers required for instrument calibration.

FDAB engineers also support flight software testing and the spacecraft Integration and Test (I&T) phase by writing software test programs and component test procedures to ensure that the flight software is written correctly and that the subsystem components are mechanically and electrically integrated to the spacecraft correctly. The ACS subsystem is also tested to verify its effect on other subsystems; there is a great deal of interaction with all the other subsystem teams. FDAB engineers support spacecraft testing from initial integration, through thermal-vacuum testing, to launch pad testing.

FDAB designs and tests the flight dynamics ground support system, of which the attitude determination system is a component. The attitude system monitors the performance of the onboard system, performs sensor calibration (the estimation of sensor misalignments, biases, and scale factors), and plans and monitors attitude maneuvers. Ground attitude estimation consists of real-time, near real-time, and offline estimates of a spacecraft attitude as well as estimates of spacecraft sensor calibration parameters. Ground attitude and sensor calibration estimation exists to provide a check on the onboard spacecraft attitude estimation, assist in resolving anomalies, and to perform computations that are too complex to be performed onboard the spacecraft.

The three modes of ground attitude and sensor calibration estimation are real-time, near real time, and offline. The real time estimation is used during critical spacecraft phases to perform checks on the spacecraft attitude and rate profile independent of the onboard estimates. An example of real time use can be seen in the MAP mission. A real time attitude system estimated the MAP attitude and rate, and this data would have been used to reinitialize the onboard attitude estimate in near real time if MAP had a gyro failure prior to or during orbit maneuvers.

The near real-time mode is used for quick onboard attitude validation for a batch of data and for quick looks at anomalies. The offline mode is used for careful study of anomalies, detailed looks of onboard attitude estimation performance, and sensor calibration.

The FDAB also supports mission simulation testing in preparation for supporting the launch and in orbit checkout of the ACS onboard and the ground attitude determination system. FDAB engineers are responsible for creating test procedures and scenarios to fully exercise the ACS and the FDS prior to conducting routine flight operations.

FDAB traditionally provides engineers to operate the ACS and the FDS until Launch and Early Orbit activities are complete and the spacecraft is transitioned to routine operations.